TEAL stands for Tokyo Electron Applications Laboratory, of Tokyo, Japan. Sinichiro Osaki in his Pocket Calculator Museum at http://www.dentaku-museum.com/ gives the information that the company was founded in 1968, sold calculators under its own TEAL brand, and was a supplier to other companies including Toshiba and Hitachi. The company went out of business in 1978 after the price of calculators plummetted.
According to the instruction manual for a TEAL 826 calculator, TEAL Industries, Inc., of Carson, California, U.S.A., was a subsidiary of Tokyo Applications Laboratory, Ltd. It marketed a range of calculators in the 1970s, in the
U.S.A. and Europe under the Teal name, including one of the first solar-powered calculators the Teal Photon.
To confuse things a little further, Tealtronic was the trade name of a British company which marketed some Japanese-made hand-held calculators in Europe under the that name. See the Tealtronic SM-8.
Examples of Teal calculators